High-precision current sensor, design method and device thereof, circuit structure and chip

Abstract

The invention relates to the technical field of electric power system current measurement, in particular to a high-precision current sensor and a design method and device thereof, a circuit structure and a chip. In the high-precision current sensor, a precision resistance Wheatstone bridge is added on the basis of an original TMR Wheatstone bridge; four precision resistors with the same resistance value are adopted, so that the four precision resistors are respectively connected in parallel at two ends of four TMR units in an original TMR Wheatstone bridge, and the resistance value of the precision resistors is smaller than that of the TMR units. According to the invention, zero offset caused by mismatching of resistance values of the TMR units is weakened, temperature offset caused by temperature is also attenuated, and the resistance value of the precision resistor is not influenced by a magnetic field, so that the influence caused by hysteresis of the TMR element is also greatly reduced, and the reliability of the TMR element is improved. Therefore, the high-precision current sensor which effectively reduces zero offset, temperature drift and hysteresis is realized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of current measurement in electric power systems, and in particular to a high-precision current sensor and a design method and device thereof, a circuit structure and a chip. Background Art

[0002] In view of the need for digital transformation of power grids and wide-area, distributed and panoramic information perception of "source, grid, load and storage" in power systems, in order to enhance the observability, measurability and controllability of power systems, it is necessary to provide high-precision perception and measurement capabilities of AC and DC magnetic fields and current signals under complex working conditions, thereby providing important guarantees for the safe operation and reliable power supply of power grid equipment.

[0003] Tunnel Magneto Resistance (TMR) is the latest generation of magnetic field measurement technology based on magnetoresistance effect. Compared with traditional Hall devices, anisotropic magnetoresistance devices and giant magnetoresistance devices, it has higher sensitivity and has broad application prospects in the field of current measurement in power systems. Specifically, the TMR device is used as a magnetic sensitive element in the current sensor to realize the TMR current sensor. The TMR current sensor adopts open-loop technology or closed-loop technology to realize the measurement of primary side current (i.e., the current to be measured).

[0004] However, due to the problems of zero bias, temperature drift and hysteresis of TMR devices, TMR current sensors cannot meet the requirements of high-precision and small current measurement, such as Figure 1 As shown. In order to solve the above problems, conditioning chips (such as temperature compensation modules, bias zeroing modules) are generally used to compensate for the temperature drift and zero bias of TMR devices, thereby improving the current measurement accuracy. However, this conventional compensation method requires the performance of the TMR device to be tested in advance and the corresponding algorithm to be used for compensation. The disadvantage of this method is that it requires performance testing of each TMR device shipped out of the factory, which is not suitable for large-scale mass production. In addition, there is generally no way to compensate for hysteresis, which is also the reason why it is difficult to detect small currents using TMR devices. Summary of the invention

[0005] In order to solve the problems in the related art, the embodiments of the present disclosure provide a high-precision current sensor and a design method and device thereof, a circuit structure, and a chip.

[0006] In a first aspect, a high-precision current sensor is provided in an embodiment of the present disclosure, comprising: a magnetic sensitive unit, the magnetic sensitive unit comprising: an input end, an output end, a TMR Wheatstone bridge and a precision resistor Wheatstone bridge;

[0007] The TMR Wheatstone bridge comprises: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, wherein the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form a bridge arm of the TMR Wheatstone bridge;

[0008] The precision resistor Wheatstone bridge comprises: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor having the same resistance value, wherein the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form a bridge arm of the precision resistor Wheatstone bridge;

[0009] Wherein, the TMR Wheatstone bridge and the precision resistor Wheatstone bridge are connected so that the first precision resistor is connected in parallel at both ends of the first TMR unit, the second precision resistor is connected in parallel at both ends of the second TMR unit, the third precision resistor is connected in parallel at both ends of the third TMR unit, the fourth precision resistor is connected in parallel at both ends of the fourth TMR unit, and the TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input end and bridge output end;

[0010] The input end of the bridge is connected to the input end and then connected to the power supply, and the output end of the bridge is connected to the output end; the resistance value of the precision resistor is smaller than the resistance value of the TMR unit.

[0011] According to an embodiment of the present disclosure, it further includes: a magnetic core, a coil, a signal processing circuit and a load resistor;

[0012] The coil is wound around the magnetic core, the magnetic sensitive unit is arranged in the open air gap of the magnetic core, the output end of the magnetic sensitive unit is connected to the input end of the signal processing circuit, the output end of the signal processing circuit is connected to the first terminal of the coil, the second terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to the reference potential.

[0013] According to an embodiment of the present disclosure, the signal processing circuit includes an operational amplifier and a power amplifier; the output end of the magnetic sensitive unit is connected to the input end of the operational amplifier, the output end of the operational amplifier is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the first terminal of the coil.

[0014] According to an embodiment of the present disclosure, the ratio of the resistance value of the precision resistor to the resistance value of the TMR unit is within a set ratio range.

[0015] According to an embodiment of the present disclosure, in the TMR Wheatstone bridge, the sensitive directions of the TMR units on adjacent bridge arms are opposite.

[0016] According to an embodiment of the present disclosure, the precision resistor includes any one of the following: a well resistor, a diffusion resistor, a polysilicon resistor, a thin film resistor, and a metal film resistor.

[0017] In a second aspect, an embodiment of the present disclosure provides a method for designing a high-precision current sensor, the method being applied to a printed circuit board (PCB) design tool, comprising:

[0018] Connect 4 precision resistor modules with the same resistance value to form a precision resistor Wheatstone bridge module;

[0019] Acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules;

[0020] The precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module are connected to obtain a magnetic sensitive unit module, in which a first precision resistor module is connected in parallel at both ends of a first TMR unit module, a second precision resistor module is connected in parallel at both ends of a second TMR unit module, a third precision resistor module is connected in parallel at both ends of a third TMR unit module, and a fourth precision resistor module is connected in parallel at both ends of a fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input and bridge output; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

[0021] According to an embodiment of the present disclosure, the precision resistor module is a chip resistor module.

[0022] According to an embodiment of the present disclosure, it also includes:

[0023] Obtain a magnetic core module, a coil module, an operational amplifier module, a power amplifier module, and a load resistor module;

[0024] connecting the coil module and the magnetic core module so that the coil module is wound around the magnetic core module;

[0025] The magnetic sensitive unit module is arranged in the open air gap of the magnetic core module;

[0026] The high-precision current sensor is obtained by connecting the output end of the magnetic sensitive unit module to the input end of the operational amplifier, connecting the output end of the operational amplifier to the input end of the power amplifier, connecting the output end of the power amplifier to the first terminal of the coil, connecting the second terminal of the coil to one end of the load resistor, and connecting the other end of the load resistor to a reference potential.

[0027] In a third aspect, an embodiment of the present disclosure provides a method for designing a high-precision current sensor, the method being applied in an electronic design automation (EDA) tool, comprising:

[0028] Obtain a precision resistor Wheatstone bridge module, wherein the precision resistor Wheatstone bridge module includes four precision resistor modules with the same resistance value;

[0029] Acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules;

[0030] The precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module are connected to form a magnetic sensitive unit module. In the magnetic sensitive unit module, a first precision resistor module is connected in parallel at both ends of the first TMR unit module, a second precision resistor module is connected in parallel at both ends of the second TMR unit module, a third precision resistor module is connected in parallel at both ends of the third TMR unit module, and a fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module. The TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance value of the precision resistor module is less than the resistance value of the TMR unit module.

[0031] According to an embodiment of the present disclosure, the precision resistor module includes a well resistor module, a diffusion resistor module, a polysilicon resistor module, a thin film resistor module, and a metal film resistor module.

[0032] In a fourth aspect, an embodiment of the present disclosure provides a design device for a high-precision current sensor, the device being applied to a printed circuit board (PCB) design tool, comprising:

[0033] A first design module is configured to connect four precision resistor modules with the same resistance value to form a precision resistor Wheatstone bridge module;

[0034] A first acquisition module is configured to acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules;

[0035] The second design module is configured to connect the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module to obtain a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance value of the precision resistor module is less than the resistance value of the TMR unit module.

[0036] In a fifth aspect, an embodiment of the present disclosure provides a design device for a high-precision current sensor, the device being applied in an electronic design automation (EDA) tool, comprising:

[0037] A third design module is configured to design a precision resistor Wheatstone bridge module, wherein the precision resistor Wheatstone bridge module includes four precision resistor modules with the same resistance value;

[0038] A second acquisition module is configured to acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules;

[0039] The fourth design module is configured to connect the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module to form a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input and bridge output; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

[0040] In a sixth aspect, a circuit structure is provided in an embodiment of the present disclosure, including: a TMR Wheatstone bridge structure and a precision resistor Wheatstone bridge structure;

[0041] The TMR Wheatstone bridge structure includes four TMR units;

[0042] The precision resistor Wheatstone bridge structure includes four precision resistors with the same resistance value;

[0043] Among them, the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure are connected so that four precision resistors are respectively connected in parallel at both ends of four TMR units, and the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure have the same bridge input end and bridge output end; the resistance value of the precision resistor is smaller than the resistance value of the TMR unit.

[0044] In a seventh aspect, a chip is provided in an embodiment of the present disclosure, comprising: a high-precision current sensor as described in any one of the first aspect, or a circuit structure as described in the sixth aspect.

[0045] In an eighth aspect, a computer-readable storage medium is provided in an embodiment of the present disclosure, on which computer instructions are stored. When the computer instructions are executed by a processor, the method described in any one of the second aspect or the third aspect is implemented.

[0046] In a ninth aspect, a computer program product is provided in an embodiment of the present disclosure, comprising computer instructions, which, when executed by a processor, implement the method as described in any one of the second aspect or the third aspect.

[0047] According to the technical solution provided by the embodiment of the present disclosure, a precision resistor Wheatstone bridge is added to the original TMR Wheatstone bridge, and four precision resistors with the same resistance are used. The resistance of the precision resistor is smaller than the resistance of the TMR unit in the TMR Wheatstone bridge, thereby weakening the zero bias caused by the mismatch of the resistance of the TMR unit, and attenuating the temperature bias caused by temperature. Since the resistance of the precision resistor is not affected by the magnetic field, the influence of the hysteresis of the TMR element is also greatly reduced, thereby effectively reducing the influence of zero bias, temperature drift and hysteresis on the high-precision current sensor. There is no need to test the performance of each TMR Wheatstone bridge, and batch compensation can be performed by knowing the approximate range of the resistance of the bridge arm of the TMR Wheatstone bridge.

[0048] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other features, objectives and advantages of the present disclosure will become more apparent through the following detailed description of non-limiting embodiments in conjunction with the accompanying drawings. In the accompanying drawings:

[0050] Figure 1 A schematic diagram of the circuit structure of a TMR Wheatstone bridge in the prior art is shown;

[0051] Figure 2 A circuit connection diagram of a high-precision current sensor according to an embodiment of the present disclosure is shown;

[0052] Figure 3 A schematic diagram showing a circuit connection of a magnetic sensitive unit in a high-precision current sensor according to an embodiment of the present disclosure is shown;

[0053] Figure 4 A circuit connection diagram of a magnetic sensitive unit in another high-precision current sensor according to an embodiment of the present disclosure is shown;

[0054] Figure 5 A flow chart showing a method for designing a high-precision current sensor according to an embodiment of the present disclosure;

[0055] Figure 6 A flow chart showing another method for designing a high-precision current sensor according to an embodiment of the present disclosure;

[0056] Figure 7A structural block diagram of a design device for a high-precision current sensor according to an embodiment of the present disclosure is shown;

[0057] Figure 8 A structural block diagram showing another device for designing a high-precision current sensor according to an embodiment of the present disclosure is shown;

[0058] Fig. 9 A schematic diagram showing the structure of a computer system suitable for implementing the method according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0059] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. In addition, for the sake of clarity, parts not related to the description of the exemplary embodiments are omitted in the accompanying drawings.

[0060] In the present disclosure, it should be understood that terms such as "include" or "have" are intended to indicate the presence of features, numbers, steps, behaviors, components, parts, or a combination thereof disclosed in the present specification, and are not intended to exclude the possibility that one or more other features, numbers, steps, behaviors, components, parts, or a combination thereof exist or are added.

[0061] It should also be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] In the present disclosure, if it involves operations of obtaining user information or user data or displaying user information or user data to others, the operations are all authorized and confirmed by the user, or actively selected by the user.

[0063] As the energy industry transforms towards clean, low-carbon, safe and efficient, power grids and new energy vehicles have an urgent need for high-sensitivity and high-reliability sensors. In the demand for high-sensitivity and high-reliability current sensors, TMR devices have higher sensitivity than traditional Hall devices, anisotropic magnetoresistive devices and giant magnetoresistive devices. Therefore, TMR devices can be used as magnetic sensitive units to realize highly sensitive TMR current sensors, and open-loop or closed-loop technology can be used to measure the magnitude of the current to be measured. Among them,

[0064] When using open-loop technology: measure the magnitude of the magnetic field generated by the primary current (i.e. the current to be measured), and infer the magnitude of the primary current through the magnitude of the magnetic field. When using closed-loop technology: form a closed-loop feedback so that the magnetic field felt by the magnetic sensitive element is always kept at zero, so that the primary current and the secondary current are in a certain ratio, and the primary current is measured.

[0065] The inventors have found that the current measurement is generally performed using a closed-loop technology. Compared with the open-loop technology, the closed-loop technology can enhance the resistance of the TMR current sensor to adverse factors such as external noise and allow the output signal to be accurately controlled and adjusted. In an ideal magnetic field-free environment, the output voltage of the TMR current sensor using the closed-loop technology is zero. However, in practice, due to factors such as the internal material properties and manufacturing process of the TMR device, the TMR device will have a non-zero output and is easily affected by temperature. It also has a hysteresis problem, which will directly affect the measurement accuracy of the TMR current sensor, especially in applications that require high-precision magnetic field measurement.

[0066] When using a conditioning chip to compensate for the temperature drift and zero bias of a TMR device, it is necessary to test the performance of the TMR device in advance and use the corresponding algorithm for compensation. It is also necessary to perform performance tests on each TMR device leaving the factory. At the same time, there is generally no way to compensate for hysteresis, which makes it difficult for TMR current sensors to detect small currents.

[0067] The present disclosure provides a high-precision current sensor, comprising: a magnetic sensitive unit, the magnetic sensitive unit comprising: an input end, an output end, a TMR Wheatstone bridge and a precision resistor Wheatstone bridge; the TMR Wheatstone bridge comprises: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form a bridge arm of the TMR Wheatstone bridge; the precision resistor Wheatstone bridge comprises: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor with the same resistance value, the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor The resistors are connected to form the bridge arms of the precision resistor Wheatstone bridge; wherein the TMR Wheatstone bridge and the precision resistor Wheatstone bridge are connected so that the first precision resistor is connected in parallel at both ends of the first TMR unit, the second precision resistor is connected in parallel at both ends of the second TMR unit, the third precision resistor is connected in parallel at both ends of the third TMR unit, and the fourth precision resistor is connected in parallel at both ends of the fourth TMR unit; the TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input end and bridge output end; the bridge input end is connected to the input end and then connected to the power supply, and the bridge output end is connected to the output end; the resistance of the precision resistor is less than the resistance of the TMR unit.

[0068] The present invention adds a precision resistor Wheatstone bridge composed of four precision resistors with the same resistance value on the basis of the original TMR Wheatstone bridge, and the resistance value of the precision resistor is smaller than the resistance value of the TMR unit in the TMR Wheatstone bridge, thereby weakening the zero bias caused by the mismatch of the resistance value of the TMR unit. In addition, since the resistance value of the precision resistor is not affected by the magnetic field and is very little affected by the temperature, the temperature bias of the high-precision current sensor is greatly attenuated, and the influence of hysteresis is also weakened.

[0069] Figure 2 A circuit connection diagram of a high-precision current sensor according to an embodiment of the present disclosure is shown.

[0070] like Figure 2 As shown, the high-precision current sensor includes: a magnetic sensitive unit, a magnetic core, a coil, a signal processing circuit and a load resistor. The coil is wound around the magnetic core, the magnetic sensitive unit is arranged in the open air gap of the magnetic core, the output end of the magnetic sensitive unit is connected to the input end of the signal processing circuit, the output end of the signal processing circuit is connected to the first terminal of the coil, the second terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to the reference potential.

[0071] According to an embodiment of the present disclosure, the signal processing circuit includes an operational amplifier and a power amplifier; the output end of the magnetic sensitive unit is connected to the input end of the operational amplifier, the output end of the operational amplifier is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the first terminal of the coil.

[0072] During operation, when the current to be measured passes through the conductor in the magnetic core, a magnetic field will be generated around the conductor (the direction and strength of the magnetic field are related to the magnitude and direction of the current), and then the generated magnetic field will be gathered by the magnetic core in the open air gap. After the magnetic sensitive unit senses the magnetic field, it outputs a voltage signal to the signal processing circuit for amplification and other processing before outputting it to the coil, so that the direction of the magnetic field generated by the current generated by the output signal on the coil is opposite to the direction of the magnetic field gathered by the magnetic core in its open air gap. When the magnetic field sensed by the magnetic sensitive unit tends to be stable, it is in a magnetic equilibrium state. At this time, the current on the load resistor forms a linear proportional relationship with the current to be measured, so the current to be measured can be obtained by measuring the current on the load resistor.

[0073] Specifically, one end of the load resistor is connected to a reference potential (i.e., a 0V potential point), and the current flowing through the load resistor can be measured by connecting a voltmeter in parallel to both ends of the load resistor or connecting an ammeter in series to the line where the load circuit is located. It can be understood by those skilled in the art that the method of measuring the current on the load resistor is not a technical means to limit the protection scope of the present disclosure, and for example, a multimeter, a digital oscilloscope, etc. can also be used.

[0074] After research, the inventor found that by connecting a precision resistor Wheatstone bridge composed of four precision resistors with the same resistance value on the basis of the TMR Wheatstone bridge, the zero bias, temperature bias and hysteresis problems caused by factors such as the internal material characteristics and manufacturing process of the TMR unit can be solved. The specific reasons are as follows:

[0075] When the TMR unit has zero bias, that is, when there is no external magnetic field, there is a certain resistance value, and this resistance value will cause a certain current to flow. However, when it is connected in parallel with the precision resistor, due to the characteristics of the parallel circuit, part of the current will flow through the precision resistor, thereby reducing the current flowing through the TMR unit, which is equivalent to compensating for the zero bias of the TMR unit.

[0076] When the TMR unit is connected in parallel with a precision resistor with a stable resistance value and is not affected by temperature, the equivalent resistance of the entire parallel circuit will be affected by both the TMR unit and the precision resistor. When the temperature changes, the resistance value of the TMR unit will change, but due to the existence of the precision resistor, the resistance change of the entire parallel circuit will be less than when the TMR unit changes alone. By connecting the precision resistor in parallel, the zero bias change of the TMR unit caused by temperature can be attenuated.

[0077] Although the parallel precision resistor itself does not directly affect the hysteresis characteristics of the TMR cell, it indirectly affects the measurement results by changing the overall response of the circuit. Specifically, since the total resistance of the parallel circuit is a function of the resistance of each branch, when the TMR cell exhibits a nonlinear response due to hysteresis, the stable resistance value of the precision resistor helps smooth the response curve of the entire circuit. When the TMR cell deviates from the ideal response due to hysteresis, the presence of the precision resistor makes the response of the entire circuit more stable and predictable, thereby helping to reduce the error caused by hysteresis.

[0078] Figure 3 A circuit connection diagram of a magnetic sensitive unit in a high-precision current sensor according to an embodiment of the present disclosure is shown. Figure 4 A circuit connection diagram of a magnetic sensitive unit in another high-precision current sensor according to an embodiment of the present disclosure is shown.

[0079] like Figure 3 and Figure 4As shown, the magnetic sensitive unit includes: an input end, an output end, a TMR Wheatstone bridge and a precision resistor Wheatstone bridge.

[0080] According to an embodiment of the present disclosure, the TMR Wheatstone bridge includes: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, and the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form a bridge arm of the TMR Wheatstone bridge.

[0081] Specifically, the resistance values ​​of the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are R TMR1 , R TMR2 , R TMR3 , R TMR4 In the ideal absence of magnetic field, R TMR1 =R TMR2 =R TMR3 =R TMR4 =0, but due to the limitations of the TMR unit's manufacturing process and device characteristics, it is difficult for the TMR unit to achieve a consistent and certain resistance value, that is, R TMR1 ≠R TMR2 ≠R TMR3 ≠R TMR4 ≠0, and R TMR1 , R TMR2 , R TMR3 , R TMR4 The values ​​are close.

[0082] According to an embodiment of the present disclosure, in the TMR Wheatstone bridge, the sensitive directions of the TMR units on adjacent bridge arms are opposite.

[0083] The sensitive direction of the TMR unit refers to the direction of the magnetic field that causes the resistance value of the TMR unit to change significantly. In the TMR Wheatstone bridge, when the sensitive directions of the TMR units on adjacent bridge arms are opposite, their responses to the same magnetic field direction will cancel each other out. For example, if the direction of the external magnetic field causes the resistance of one TMR unit to increase, the resistance of another adjacent TMR unit (with the opposite sensitive direction) will decrease accordingly. In this way, the changes of the two TMR units cancel each other out in the bridge, making the output of the bridge more stable.

[0084] According to an embodiment of the present disclosure, the precision resistor Wheatstone bridge includes: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor with the same resistance value. The first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form a bridge arm of the precision resistor Wheatstone bridge.

[0085] Specifically, the resistance values ​​of the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are R1, R2, R3, and R4, respectively, and R1=R2=R3=R4.

[0086] It is known that precision resistors have the characteristics of high stability, high accuracy and low temperature drift, and the resistance error of precision resistors is very small. For resistors with a resistance value of more than 1 ohm, the resistance error within ±0.5% can be called precision resistors. Precision resistors with higher precision can achieve an accuracy of 0.01%, that is, an error range of one ten-thousandth.

[0087] In one implementation, R1 = R2 = R3 = R4 can be easily achieved as long as the accuracy is high enough.

[0088] In another embodiment, the precision resistor does not need a very precise absolute resistance value, as long as the resistance consistency on the four bridge arms is ensured, so that the resistance value and temperature drift are better matched. Since this method does not require high accuracy of the absolute value of the precision resistor, the difficulty of preparing the precision resistor can be greatly reduced.

[0089] According to the embodiments of the present disclosure, the precision resistor may generally include any one of the following: a well resistor, a diffusion resistor, a polysilicon resistor, a thin film resistor, a metal film resistor, a metal foil resistor, a wirewound resistor, and the like.

[0090] Among them, the TMR Wheatstone bridge and the precision resistor Wheatstone bridge are connected so that the first precision resistor is connected in parallel at both ends of the first TMR unit, the second precision resistor is connected in parallel at both ends of the second TMR unit, the third precision resistor is connected in parallel at both ends of the third TMR unit, and the fourth precision resistor is connected in parallel at both ends of the fourth TMR unit. The TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input end and bridge output end.

[0091] The input end of the bridge is connected to the input end and then connected to the power supply, and the output end of the bridge is connected to the output end; the resistance value of the precision resistor is smaller than the resistance value of the TMR unit.

[0092] According to an embodiment of the present disclosure, the ratio of the resistance value of the precision resistor to the resistance value of the TMR unit is within a set ratio range.

[0093] It is known that when the TMR unit has zero bias, that is, when there is no external magnetic field, it also has a certain resistance value, and this resistance value will cause a certain current to flow. However, when it is connected in parallel with the precision resistor, due to the characteristics of the parallel circuit, part of the current will flow through the precision resistor, thereby reducing the current flowing through the TMR unit, which is equivalent to compensating for the zero bias of the TMR unit.

[0094] The specific ratio of the resistance of the precision resistor to the resistance of the TMR unit can be adjusted as needed, for example, the ratio range is set between 1:20 and 1:5. The smaller the ratio is, the better the effect of zero bias and temperature drift compensation is, but it will also affect the sensitivity of the magnetic sensitive unit. Therefore, the ratio range needs to be determined based on the overall accuracy requirements of the high-precision current sensor and the noise and gain of the back-end signal processing circuit.

[0095] The present invention weakens the zero bias caused by the mismatch of the resistance value of the TMR unit, and also attenuates the temperature bias caused by temperature. Since the resistance value of the precision resistor is not affected by the magnetic field, the influence caused by the hysteresis of the TMR element is also greatly reduced, thereby effectively reducing the influence of zero bias, temperature drift and hysteresis on the high-precision current sensor.

[0096] At the same time, the present invention can not only realize a high-precision current sensor, but also does not need to test the performance of the TMR Wheatstone bridge in each high-precision current sensor. It only needs to know the approximate range of the resistance of the bridge arm of the TMR Wheatstone bridge to perform batch compensation. This is because the existence of the precision resistor Wheatstone bridge reduces the impact of the resistance change of the TMR unit. Therefore, it is only necessary to know the approximate range of the resistance of the bridge arm of the TMR Wheatstone bridge to perform batch compensation, thereby realizing batch manufacturing.

[0097] Figure 5 A flow chart showing a method for designing a high-precision current sensor according to an embodiment of the present disclosure is shown; the method is applied to a printed circuit board (PCB) design tool, such as Figure 5 As shown, the method 500 includes steps S501 to S503:

[0098] In step S501 , four precision resistor modules with the same resistance value are connected to form a precision resistor Wheatstone bridge module.

[0099] In step S502, a TMR Wheatstone bridge module is obtained, where the TMR Wheatstone bridge module includes four TMR unit modules.

[0100] In step S503, the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module are connected to obtain a magnetic sensitive unit module, in which a first precision resistor module is connected in parallel at both ends of the first TMR unit module, a second precision resistor module is connected in parallel at both ends of the second TMR unit module, a third precision resistor module is connected in parallel at both ends of the third TMR unit module, and a fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input and bridge output; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

[0101] According to an embodiment of the present disclosure, the precision resistor module is a chip resistor module.

[0102] When the high-precision current sensor is manufactured by the above method, the precision resistors can use precision chip resistors to form a precision resistor Wheatstone bridge on a PCB board, and then be connected to the TMR Wheatstone bridge.

[0103] According to an embodiment of the present disclosure, the method 500 further includes the following steps S504 to S507:

[0104] In step S504, a magnetic core module, a coil module, an operational amplifier module, a power amplifier module, and a load resistance module are obtained;

[0105] In step S505, the coil module and the magnetic core module are connected so that the coil module is wound around the magnetic core module;

[0106] In step S506, the magnetic sensitive unit module is arranged in the open air gap of the magnetic core module;

[0107] In step S507, the output end of the magnetic sensitive unit module is connected to the input end of the operational amplifier, the output end of the operational amplifier is connected to the input end of the power amplifier, the output end of the power amplifier is connected to the first terminal of the coil, the second terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to a reference potential to obtain the high-precision current sensor.

[0108] Figure 6 A flow chart of another method for designing a high-precision current sensor according to an embodiment of the present disclosure is shown; the method is applied in an electronic design automation (EDA) tool, and the method includes steps S601 to S603:

[0109] In the step S601, a precision resistor Wheatstone bridge module is obtained, and the precision resistor Wheatstone bridge module includes four precision resistor modules with the same resistance value.

[0110] In the step S602, a TMR Wheatstone bridge module is obtained, and the TMR Wheatstone bridge module includes four TMR unit modules.

[0111] In the step S603, the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module are connected to form a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

[0112] According to an embodiment of the present disclosure, the precision resistor module is a well resistor module, a diffusion resistor module, a polysilicon resistor module, a thin film resistor module, or a metal film resistor module.

[0113] When the high-precision current sensor is manufactured by the above method, the precision resistors in the precision resistor Wheatstone bridge and the TMR units in the TMR Wheatstone bridge can be manufactured on a chip by ion implantation or the like, thereby realizing the high-precision current sensor on the chip.

[0114] Figure 7 A structural block diagram of a design device for a high-precision current sensor according to an embodiment of the present disclosure is shown; the device is applied to a PCB design tool, such as Figure 7 As shown, the device 700 includes: a first design module 701 , a first acquisition module 701 , and a second design module 703 .

[0115] The first design module 701 is configured to connect four precision resistor modules with the same resistance value to form a precision resistor Wheatstone bridge module.

[0116] The first acquisition module 701 is configured to acquire a TMR Wheatstone bridge module, and the TMR Wheatstone bridge module includes four TMR unit modules.

[0117] The second design module 703 is configured to connect the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module to obtain a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

[0118] Figure 8 A structural block diagram of another high-precision current sensor design device according to an embodiment of the present disclosure is shown; the device is applied in an EDA tool, such as Figure 8 As shown, the device 800 includes: a third design module 801 , a second acquisition module 802 , and a fourth design module 803 .

[0119] The third design module 801 is configured to design a precision resistor Wheatstone bridge module, wherein the precision resistor Wheatstone bridge module includes four precision resistor modules with the same resistance value;

[0120] The second acquisition module 802 is configured to acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules;

[0121] The fourth design module 803 is configured to connect the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module to form a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

[0122] The present disclosure also provides a circuit structure, including: a TMR Wheatstone bridge structure and a precision resistor Wheatstone bridge structure; the TMR Wheatstone bridge structure includes four TMR units; the precision resistor Wheatstone bridge structure includes four precision resistors with the same resistance; wherein the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure are connected so that the four precision resistors are respectively connected in parallel at both ends of the four TMR units, and the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure have the same bridge input end and bridge output end; the resistance of the precision resistor is less than the resistance of the TMR unit.

[0123] The present disclosure also provides a chip, comprising: the high-precision current sensor as described above, or the circuit structure as described above.

[0124] Fig. 9 A schematic diagram showing the structure of a computer system suitable for implementing the method according to an embodiment of the present disclosure is shown.

[0125] like Fig. 9 As shown, the computer system includes a processing unit, which can perform the various methods in the above-mentioned embodiments according to the program stored in the read-only memory (ROM) or the program loaded from the storage part into the random access memory (RAM). In the RAM, various programs and data required for the operation of the computer system are also stored. The processing unit, ROM and RAM are connected to each other through a bus. The input / output (I / O) interface is also connected to the bus.

[0126] The following components are connected to the I / O interface: an input part including a keyboard, a mouse, etc.; an output part including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker; a storage part including a hard disk, etc.; and a communication part including a network interface card such as a LAN card, a modem, etc. The communication part performs a communication process via a network such as the Internet. The drive is also connected to the I / O interface as needed. Removable media, such as disks, optical disks, magneto-optical disks, semiconductor memories, etc., are installed on the drive as needed so that the computer program read therefrom is installed into the storage part as needed. Among them, the processing unit can be implemented as a processing unit such as a CPU, a GPU, a TPU, an FPGA, an NPU, etc.

[0127] In particular, according to an embodiment of the present disclosure, the method described above can be implemented as a computer software program. For example, an embodiment of the present disclosure includes a computer program product, which includes a computer program tangibly contained on a machine-readable medium, and the computer program includes a program code for executing the above method. In such an embodiment, the computer program can be downloaded and installed from a network through a communication part, and / or installed from a removable medium.

[0128] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0129] The units or modules involved in the embodiments described in the present disclosure may be implemented by software or programmable hardware. The units or modules described may also be set in a processor, and the names of these units or modules do not constitute limitations on the units or modules themselves in some cases.

[0130] As another aspect, the present disclosure further provides a computer-readable storage medium, which may be a computer-readable storage medium included in the computer system in the above embodiment; or a computer-readable storage medium that exists independently and is not assembled into a device. The computer-readable storage medium stores one or more programs, and the programs are used by one or more processors to execute the method described in the present disclosure.

[0131] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present disclosure is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present disclosure (but not limited to) by each other.

Claims

1. A high-precision current sensor, characterized in that: include: A magnetic sensitive unit, the magnetic sensitive unit comprising: an input end, an output end, a tunneling magnetoresistor TMR Wheatstone bridge and a precision resistor Wheatstone bridge; The TMR Wheatstone bridge comprises: a first TMR unit, a second TMR unit, a third TMR unit, and a fourth TMR unit, wherein the first TMR unit, the second TMR unit, the third TMR unit, and the fourth TMR unit are connected to form a bridge arm of the TMR Wheatstone bridge; The precision resistor Wheatstone bridge comprises: a first precision resistor, a second precision resistor, a third precision resistor, and a fourth precision resistor having the same resistance value, wherein the first precision resistor, the second precision resistor, the third precision resistor, and the fourth precision resistor are connected to form a bridge arm of the precision resistor Wheatstone bridge; Wherein, the TMR Wheatstone bridge and the precision resistor Wheatstone bridge are connected so that the first precision resistor is connected in parallel at both ends of the first TMR unit, the second precision resistor is connected in parallel at both ends of the second TMR unit, the third precision resistor is connected in parallel at both ends of the third TMR unit, the fourth precision resistor is connected in parallel at both ends of the fourth TMR unit, and the TMR Wheatstone bridge and the precision resistor Wheatstone bridge have the same bridge input end and bridge output end; The input end of the bridge is connected to the input end and then connected to the power supply, and the output end of the bridge is connected to the output end; the resistance value of the precision resistor is smaller than the resistance value of the TMR unit.

2. The high-precision current sensor according to claim 1, characterized in that: Also includes: a magnetic core, a coil, a signal processing circuit and a load resistor; The coil is wound around the magnetic core, the magnetic sensitive unit is arranged in the open air gap of the magnetic core, the output end of the magnetic sensitive unit is connected to the input end of the signal processing circuit, the output end of the signal processing circuit is connected to the first terminal of the coil, the second terminal of the coil is connected to one end of the load resistor, and the other end of the load resistor is connected to the reference potential.

3. The high-precision current sensor according to claim 2, characterized in that: The signal processing circuit includes an operational amplifier and a power amplifier; the output end of the magnetic sensitive unit is connected to the input end of the operational amplifier, the output end of the operational amplifier is connected to the input end of the power amplifier, and the output end of the power amplifier is connected to the first terminal of the coil.

4. The high-precision current sensor according to claim 1, characterized in that: The ratio of the resistance value of the precision resistor to the resistance value of the TMR unit is within a set ratio range.

5. The high-precision current sensor according to claim 1, characterized in that: In the TMR Wheatstone bridge, the sensitive directions of the TMR units on adjacent bridge arms are opposite.

6. The high-precision current sensor according to claim 1, characterized in that: The precision resistor includes any one of the following: a well resistor, a diffusion resistor, a polysilicon resistor, a thin film resistor, and a metal film resistor.

7. A design method for a high-precision current sensor, characterized in that: The method is applied to a printed circuit board (PCB) design tool, and comprises: Connect 4 precision resistor modules with the same resistance value to form a precision resistor Wheatstone bridge module; Acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules; The precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module are connected to obtain a magnetic sensitive unit module, in which a first precision resistor module is connected in parallel at both ends of a first TMR unit module, a second precision resistor module is connected in parallel at both ends of a second TMR unit module, a third precision resistor module is connected in parallel at both ends of a third TMR unit module, and a fourth precision resistor module is connected in parallel at both ends of a fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input and bridge output; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

8. The method according to claim 7, characterized in that The precision resistor module is a chip resistor module.

9. The method according to claim 7, characterized in that: Also includes: Obtain a magnetic core module, a coil module, an operational amplifier module, a power amplifier module, and a load resistor module; connecting the coil module and the magnetic core module so that the coil module is wound around the magnetic core module; The magnetic sensitive unit module is arranged in the open air gap of the magnetic core module; The high-precision current sensor is obtained by connecting the output end of the magnetic sensitive unit module to the input end of the operational amplifier, connecting the output end of the operational amplifier to the input end of the power amplifier, connecting the output end of the power amplifier to the first terminal of the coil, connecting the second terminal of the coil to one end of the load resistor, and connecting the other end of the load resistor to a reference potential.

10. A design method for a high-precision current sensor, characterized in that: The method is applied in an electronic design automation (EDA) tool, and includes: Obtain a precision resistor Wheatstone bridge module, wherein the precision resistor Wheatstone bridge module includes four precision resistor modules with the same resistance value; Acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules; The precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module are connected to form a magnetic sensitive unit module. In the magnetic sensitive unit module, a first precision resistor module is connected in parallel at both ends of the first TMR unit module, a second precision resistor module is connected in parallel at both ends of the second TMR unit module, a third precision resistor module is connected in parallel at both ends of the third TMR unit module, and a fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module. The TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance value of the precision resistor module is less than the resistance value of the TMR unit module.

11. The method according to claim 10, characterized in that include: The precision resistor module is a well resistor module, a diffusion resistor module, a polysilicon resistor module, a thin film resistor module, and a metal film resistor module.

12. A design device for a high-precision current sensor, characterized in that: The device is applied to a printed circuit board (PCB) design tool, and comprises: A first design module is configured to connect four precision resistor modules with the same resistance value to form a precision resistor Wheatstone bridge module; A first acquisition module is configured to acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules; The second design module is configured to connect the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module to obtain a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input terminal and bridge output terminal; wherein the resistance value of the precision resistor module is less than the resistance value of the TMR unit module.

13. A design device for a high-precision current sensor, characterized in that: The device is applied to an electronic design automation (EDA) tool, and includes: A third design module is configured to design a precision resistor Wheatstone bridge module, wherein the precision resistor Wheatstone bridge module includes four precision resistor modules with the same resistance value; A second acquisition module is configured to acquire a TMR Wheatstone bridge module, wherein the TMR Wheatstone bridge module includes four TMR unit modules; The fourth design module is configured to connect the precision resistor Wheatstone bridge module and the TMR Wheatstone bridge module to form a magnetic sensitive unit module, in which the first precision resistor module is connected in parallel at both ends of the first TMR unit module, the second precision resistor module is connected in parallel at both ends of the second TMR unit module, the third precision resistor module is connected in parallel at both ends of the third TMR unit module, and the fourth precision resistor module is connected in parallel at both ends of the fourth TMR unit module, and the TMR Wheatstone bridge module and the precision resistor Wheatstone bridge module have the same bridge input and bridge output; wherein the resistance of the precision resistor module is less than the resistance of the TMR unit module.

14. A circuit structure, characterized in that: include: TMR Wheatstone bridge structure and precision resistor Wheatstone bridge structure; The TMR Wheatstone bridge structure includes four TMR units; The precision resistor Wheatstone bridge structure includes four precision resistors with the same resistance value; Among them, the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure are connected so that four precision resistors are respectively connected in parallel at both ends of four TMR units, and the TMR Wheatstone bridge structure and the precision resistor Wheatstone bridge structure have the same bridge input end and bridge output end; the resistance value of the precision resistor is smaller than the resistance value of the TMR unit.

15. A chip, characterized in that: include: A high-precision current sensor as claimed in any one of claims 1 to 6, or a circuit structure as claimed in claim 14.

16. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by a processor, the method described in any one of claims 7 to 11 is implemented.

17. A computer program product, comprising computer instructions, which implement the method according to any one of claims 7 to 11 when executed by a processor.

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